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By Benjamin Kahane

Nuclear energy isn’t quite a fossil fuel, since unlike coal, natural gas and petroleum, nuclear is not powered by fuel that developed over millennia from pressurized dead organisms — but nuclear isn’t renewable, either, since it uses a finite non-renewable fuel source. Nuclear power also presents many environmental problems, such as how to handle its radioactive waste product, and, in extreme circumstances, is disastrous, such as in Chernobyl, Ukraine, and recently in Japan.

Nuclear energy is derived from the splitting of an atom, most commonly an isotope of uranium with an atomic mass of 235. The process is called fission.

In a nuclear reactor, fission events are induced by the bombardment of atoms with neutrons. Splitting an atom of uranium consumes about 7 to 8 million electron volts and each fission event creates about 200 million electron volts for a 25:1 power-output ratio. This generated energy heats water, which turns into steam and powers a turbine to create electricity.

Currently 104 nuclear reactors operate at 64 power plants across the United States, providing America with about 20 percent of its electricity.

Nuclear power is sometimes confused as a sustainable or renewable power. It is not, simply because there is a finite amount of uranium and plutonium on Earth. Nuclear power does not create any greenhouse gasses or expel any other environmentally harmful gasses into the atmosphere. However, fossil fuels are used in the mining for uranium, the uranium enrichment process, transportation of the nuclear fuel, and of course the erection of the power plant. It is difficult to quantify the fossil fuels burnt for nuclear power, but so much power can be extracted from the fission process that the power generated dwarfs the amount of harmful gasses emitted into the atmosphere compared to a coal or natural-gas plant.

Of course there is another completely unique harmful agent as a result of nuclear energy: radioactive nuclear waste. Once the fuel is spent, it must be stored safely, and this is a major point of contention among advocates and opponents of this source of energy. Governments around the globe are considering different types of nuclear-waste management options, although the most prevalent involve deep geologic placement — burying it deep in the earth, perhaps under a mountain. The main issue is that we are dealing with a threat that has a life span of 10,000 to millions of years.

With the recent nuclear emergencies at Japan’s Fukushima nuclear reactor, many countries are reevaluating their current safety measures in existing plants. Given the gravity of the hazardous radioactive waste as a byproduct of this type of energy production, it is not surprising that no new nuclear plants have opened in the United States since 1996. And before then, the last time that a nuclear plant was approved to be built was before Pennsylvania’s Three Mile Island nuclear meltdown in 1979. But we may be entering a new nuclear era: In February 2012, the U.S. Nuclear Regulatory Commission approved licenses for two new reactors to be built at an existing nuclear plant in Georgia. Applications for an additional 25 nuclear plants across the country are pending.

Benjamin Kahane is a utility-scale project engineer at SunEdison, where he designs photovoltaic solar-energy systems. He earned his master’s degree in sustainable-energy engineering at the University of Maryland, College Park.